The Importance of a Timing Chain Guide

A timing chain guide is a component that is responsible for maintaining the proper alignment of the cam and crank sprockets. These guides help to prevent the chain from elongating, which can cause a variety of problems including a loss of engine power, a failed valve train or even a complete engine failure. If your vehicle is showing signs of a worn or damaged guide, then it is time to replace it. Here at Dolz, we offer a full kit that includes the replacement chain, tensioner, guides and cam and crank sprockets.

In the old days of pushrod motors and much shorter cam chains, a chain would last the life of the car without any tensioner or guides. Today, modern OHC engines have much longer, multi-cam chains and the use of a tensioner helps to extend the longevity of these parts. However, the stresses of high mileage and poor maintenance can still hasten the wear of these important components.

Timing chains largely replaced gear-driven systems (or shaft and bevel gear systems) because they are easier to package, lighter and more efficient than their predecessors. However, the chain must be properly maintained and lubricated or it will cause a variety of problems including a noisy, sluggish engine or a loss of power. In addition, if the chain is not properly synchronized with the sprockets it can elongate and a variety of CEL codes will show up on the vehicle’s check engine display.

While there are some cases where a chain may be fine and will run well for many miles, it is a good idea to change it every 80,000 or 120,000 miles to avoid potential issues. Changing the chain is an easy job and most mechanics will do it for you at a fair price.

During the course of a typical engine’s lifespan, the timing chain will encounter multiple stress cycles. These cycles include the abrasive force of the cam sprockets and crankshaft as they pass by each other. They also include the heat and mechanical stresses of thousands of heat and cool cycles. These forces can wear the chain, sprockets and guide rails. If the chain is not lubricated properly or the tensioner fails, it can result in the chains contacting and damaging the guide rails.

Typically, plastic timing chain guide rails are used in conjunction with metal chain tensioners. Over time and through abrasions, these plastic guides can crack and break, as they are subject to the same mechanical stresses and heat cycles that the chain goes thru. These fractures and cracks can allow the chain to slap against them which can damage the guides and cause oil leaks. If a broken guide rail is not replaced, it will be subject to further damage over time. We recommend replacing the lower and upper chain guide rails when a new chain is installed to ensure that the system is returned to like-new condition.